Method of applying a laser beam around the circumference of a catheter

ABSTRACT

A polymeric material may be bonded to a polymeric catheter tube by generating at least one annular beam of electromagnetic energy at a wavelength that is at least partially absorbed by at least one of the polymeric material and the polymeric catheter tube, controllably directing the annular beam of energy onto the polymeric material to concentrate the energy in a bond site circumscribing the catheter tube to at least partially melt at least one material selected from the group consisting of the polymeric material and the polymeric catheter tube along the bond site and the immediate region thereof and allowing the at least one partially melted polymeric material to cool and solidify to form a fusion bond between the tube and the polymeric material.

STATEMENT OF RELATED APPLICATION

[0001] This application is a continuation and claims the benefit ofpriority to co-pending U.S. patent application Ser. No. 09/654,987,filed Sep. 5, 2000, entitled “Method of Applying A Laser Beam Around TheCircumference Of A Catheter,” the specification of which is incorporatedherein by reference in its entirety.

BACKGROUND OF THE INVENTION

[0002] Medical catheters having a balloon mounted thereon are useful ina variety of medical procedures. Balloon catheters may be used to widena vessel into which the catheter is inserted by dilating the blockedvessel, such as in an angioplasty procedure. Balloon catheters may alsobe used to expand and/or seat a medical device such as a stent or graftat a desired position within a body lumen. In all of these applications,fluid under pressure is supplied to the balloon through an inflationlumen in the catheter, thereby expanding the balloon.

[0003] It is essential in the manufacture of balloon catheters toproperly seal the balloon to the catheter. The seal must be able towithstand the high pressures to which it is subjected on inflation ofthe balloon. A poor seal may result in leakage of inflation fluid andinability to achieve the desired pressure or even rapid loss of pressureand deflation of the balloon.

[0004] A number of methods for sealing a balloon to a catheter are knownin the art. One such method involves the use of a suitable adhesive tobond the balloon to the catheter tube as disclosed, iter alia, in U.S.Pat. No. 4,913,701 to Tower and U.S. Pat. No. 4,943,278 to Euteneuer etal. The use of adhesives, however, adds to the thickness of the catheterand increase its rigidity at the region of the bonds. Moreover, adhesivebonds are known to be generally inferior to fusion bonds.

[0005] Another such method, where heat fusible materials are employed,involves the application of heat to fuse the balloon to the cathetertube. To that end, resistance heating of copper jaws has been employedto fuse a balloon to a catheter tube. Resistance heating, however, isknown to result in the formation of small, random channels at theballoon-catheter interface, giving rise to undesirable variations in thestrength of different bonds. The heat also causes undesirablecrystallization and stiffening of the balloon and catheter material, notonly at the bond site, but also in both directions axially of the bond,due to heat conduction through the balloon and the catheter, and heatradiation from the jaws.

[0006] A non-contact method for heat sealing a balloon onto a catheteris disclosed in U.S. Pat. No. 4,251,305 to Becker et al. A length ofthin tubing is slid over an elongated shaft of the catheter and shrinktubing installed over the thin walled tubing at its ends overlapping thecatheter shaft. The shrink tubing is partially shrunk. Lamps emittingenergy along the visible and infrared spectra are used to provideradiant energy to form gradually tapering thermoplastic joints that bondthe tubing and shaft. This method, nevertheless, suffers from theproblem of undesired heat transfer along the catheter and balloon.

[0007] Yet another fusion-based method disclosed in U.S. Pat. No.5,501,759 to Forman involves the use of a beam of laser radiation at awavelength selected to at least approximately match a wavelength ofmaximum spectral absorption of the polymeric materials forming theballoon member and body. The polymeric materials are melted by theradiation and then allowed to cool and solidify to form a fusion bondbetween the catheter tube and the balloon. In order to bond the balloonabout its entire circumference to the catheter tube, the catheter tubemay be rotated relative to the laser beam or the laser beam may berotated relative to the catheter tube.

[0008] In the former case, rotation speeds of 400 rpm or higher arenecessary to ensure even heating of the catheter tube and balloonmaterial. Care must be taken, however, to avoid damaging the catheterduring rotation. Where a stent is mounted on the balloon, rotation ofthe catheter is even more difficult because of issues of stentsecurement. Moreover, the process can be slow because of the timerequired for the motor to attain the desired speed.

[0009] In the latter case, rotation of the beam relative to the cathetermay be effected via the use of mirrors and focusing lenses. Alignment isdifficult to achieve and maintain in such a system because of vibrationfrom moving parts. The process is slow because of the time involved inloading and unloading the catheter and waiting for the rotational beamto reach the desired speed. Moreover, such an arrangement can beexpensive to build.

[0010] Another fusion-based method disclosed in Forman involves thesimultaneous use of multiple beams of energy to supply energy atdiscrete points about the circumference of the balloon and thereby heatthe balloon. A single beam is split into multiple discrete beams and themultiple discrete beams directed about the circumference of the balloonvia fiber optics.

[0011] For the purpose of this disclosure, all US patents and patentapplications referenced herein are incorporated herein by reference intheir entirety.

[0012] The invention in various of its embodiment is summarized below.Additional details of the invention and/or additional embodiments of theinvention may be found in the Detailed Description of the Inventionbelow.

BRIEF SUMMARY OF THE INVENTION

[0013] The instant invention in some of its embodiments provides a novelprocess for sealing a polymeric balloon material to a polymeric cathetertube.

[0014] In one embodiment, the invention is directed to a process forsealing at least one polymeric material to a polymeric catheter tube. Inaccordance with the process, a polymeric material and a polymericcatheter tube are provided. A source of energy is also provided. Atleast one wavelength of energy that is at least partially absorbed by atleast one of the polymeric material and the polymeric catheter tube isselected and at least one annular beam of electromagnetic energygenerated at said selected energy wavelength. The annular beam of energyis controllably directed onto the polymeric material to concentrate theenergy in a bond site circumscribing the catheter tube to at leastpartially melt at least one material selected from the group consistingof the polymeric material and the polymeric catheter tube along the bondsite and the immediate region thereof. Both materials may be heateddirectly by the energy beam and/or the at least one melted material maymelt adjoining materials by conduction/heat transfer. After cooling, thetwo materials have mixed and re-solidified to form a fusion bond betweenthe tube and the polymeric material. Desirably, the polymeric materialis a polymeric balloon material.

[0015] In another embodiment, the invention is directed to a process forforming a fluid tight seal between a polymeric body and a polymericdilatation member surrounding the polymeric body. The method comprisesthe steps of positioning a dilatation member of polymeric material alongand in surrounding relation to a body of polymeric material with thedilatation member and body aligned to place a first surface portion ofthe dilatation member and a second surface portion of the body in acontiguous and confronting relation. The polymeric materials forming thebody and the dilatation member may have non-uniform energy absorptionspectra that include high absorptivity wavelength bands. At least one ofthe high absorptivity wavelength bands of the polymeric material formingthe body and at least one of the high absorptivity wavelength bands ofthe polymeric material forming the dilatation member overlap one anotherin at least one range of overlapping wavelengths. A monochromatic energywavelength that is contained within at least one of the overlappingwavelength ranges is selected and an annular beam of substantiallymonochromatic electromagnetic energy generated at said selectedmonochromatic energy wavelength. The annular beam of substantiallymonochromatic energy is controllably directed onto the polymeric bodyand the dilatation member to concentrate the monochromatic energy in anarrow bond site circumscribing the body and running along the interfaceof the first and second surface portions to melt the polymeric materialsalong the bond site and the immediate region thereof. The previouslymelted polymeric material is then allowed to cool and solidify to form afusion bond between the body and dilatation member.

[0016] In another embodiment, the invention is directed to a process forsimultaneously bonding at least two polymeric materials to a cathetertube. The process comprises the steps of providing a catheter tubehaving at least a first predetermined bonding location and a secondpredetermined bonding location for bonding a polymeric material thereto,each bonding location having a polymeric material circumscribing thecatheter tube at the bonding location. A first annular beam ofelectromagnetic energy that is at least partially absorbed by thepolymeric material at the first bonding location and a second annularbeam of electromagnetic energy that is at least partially absorbed bythe polymeric material at the second bonding location are simultaneouslygenerated. The first and second annular beams of energy are controllablydirected onto the polymeric balloon material at the first and secondpredetermined bonding locations to concentrate the energy into the firstand second predetermined bond sites circumscribing the catheter tube andto at least partially melt the polymeric balloon material along the bondsites and the immediate regions thereof. The previously melted polymericmaterials in the first and second bonding locations are allowed tosolidify to form fusion bonds between the catheter tube and thepolymeric material at the first and second bonding locations.

[0017] In yet another embodiment, the invention is directed to a processfor simultaneously welding the proximal and distal ends of a balloonmade of polymeric material to a catheter tube. The process comprises thesteps of generating a first annular beam of electromagnetic energy at awavelength that is at least partially absorbed by the balloon and asecond annular beam of electromagnetic energy at a wavelength that is atleast partially absorbed by the balloon, controllably directing thefirst annular beam toward the proximal end of the balloon to concentratethe energy in a narrow bond site circumscribing the catheter tube andrunning along the interface of the catheter tube and the proximal end ofthe balloon thus to melt the polymeric materials along said bond siteand the immediate region thereof, simultaneously controllably directingthe second annular beam toward the distal end of the balloon toconcentrate the energy in a narrow bond site circumscribing the cathetertube and running along the interface of the first and second surfaceportions, thus to melt the polymeric materials along the bond site andthe immediate region thereof and allowing the previously meltedpolymeric material to cool and solidify to form a fusion bond betweenthe catheter tube and the proximal and distal ends of the balloon.

[0018] In yet another embodiment, the invention is directed to a processfor bonding at least one polymeric material to a polymeric cathetertube. The method comprises the steps of generating at least one annularbeam of electromagnetic energy that is at least partially absorbed by atleast one of the polymeric material and the polymeric catheter tube atsaid selected energy wavelength, controllably directing at least aportion of the annular beam of energy onto the polymeric material toconcentrate the energy in a bond site circumscribing at least a portionof the polymeric catheter tube to at least partially melt at least onematerial selected from the group consisting of the polymeric materialand the polymeric catheter tube along the bond site and the immediateregion thereof and allowing the at least one partially melted polymericmaterial to cool and solidify to form a fusion bond between thepolymeric catheter tube and the polymeric material.

[0019] A detailed description of the invention in its variousembodiments is provided below.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

[0020]FIG. 1 shows a side elevational view of the distal end of aballoon catheter;

[0021]FIG. 2 shows an enlarged cross-sectional view of a portion of theballoon catheter of FIG. 1;

[0022]FIG. 3 is a schematic view of an apparatus employed in theinventive process;

[0023]FIG. 4 shows the evolution of the beam of FIG. 3 in threedimensions;

[0024]FIG. 5a is a schematic view of fixture for holding a catheter;

[0025]FIG. 5b is an isometric view of the fixture of FIG. 5a;

[0026]FIG. 5c is an end view of the fixture of FIG. 5a;

[0027]FIGS. 5d and 5 e are schematic views of other fixtures for holdinga catheter;

[0028]FIG. 5f is an isometric view of the fixture of FIG. 5e;

[0029]FIG. 6 is a schematic view of another apparatus that may beemployed in the inventive process;

[0030]FIG. 7 is a schematic view of an apparatus similar to that of FIG.6 with a larger focus beam;

[0031]FIG. 8 is a schematic view of another apparatus that may beemployed in the inventive process;

[0032]FIG. 9 is a schematic side elevational view of a balloon with heatshrink tubing disposed thereon;

[0033]FIGS. 10 and 11 depict a substantially constant profile and aGaussian profile, respectively, of a laser beam with the intensity ofthe beam plotted as a function of location along the beam diameter;

[0034]FIG. 12 is a schematic view of another apparatus that may beemployed in the inventive process;

[0035]FIG. 13 is a schematic view of another apparatus that may beemployed in the inventive process;

[0036]FIG. 14 is a schematic sectional side view of a catheter tubehaving a stent and retention sleeves disposed thereon;

[0037]FIG. 15a is a schematic sectional side view of a portion anotherapparatus that may be employed in the inventive process; and

[0038]FIG. 15b is an end view of the apparatus of FIG. 15a.

DETAILED DESCRIPTION OF THE INVENTION

[0039] While this invention may be embodied in many different forms,there are described in detail herein specific preferred embodiments ofthe invention. This description is an exemplification of the principlesof the invention and is not intended to limit the invention to theparticular embodiments illustrated.

[0040] As used herein, the term “annular” encompasses ringlike shapesincluding those with a circular periphery and those with a non-circularperiphery. An example of the latter is a ring whose periphery iselliptical.

[0041] Turning to the drawings, the distal end region of a ballooncatheter is shown generally at 100 in FIG. 1. The balloon catheterincludes an elongated and pliable length of catheter tubing 104constructed of a body compatible polymeric material such as a polyester.Desirably, a polyester such as Hytrel® may be used. Other suitablematerials include polyolefins, polyamides and thermoplasticpolyurethanes, and copolymers of these materials. A balloon 108surrounds catheter tubing 104 along the distal end region. The balloonis shown in its fully expanded configuration, as when the ballooncontains a fluid, supplied under pressure to the balloon interiorthrough a balloon inflation lumen (not shown) open to the proximal endof catheter tubing 104 and to the balloon interior.

[0042] Fully expanded, balloon 108 includes a main body region 112,disposed about catheter tubing 104, and with a diameter substantiallylarger than that of the tubing. The appropriate balloon and cathetertubing diameters vary, depending upon factors such as the size of thevessel or other body cavity, and the procedure involved. At oppositeends of main body region 112 are a proximal cone 116, and a distal cone120. The proximal cone terminates in a proximal neck region 124. Theinner diameter of neck region 124 is substantially equal to the outerdiameter of catheter tubing 104 in the region of the proximal neck toprovide an interface region along which the interior surface of neckregion 124 and the exterior surface of catheter tubing 104 confront oneanother and are contiguous.

[0043] Distal cone 120 similarly terminates in a distal neck region 128.The distal neck also has an inner diameter substantially equal to theouter diameter of catheter tubing 104 in the region of the distal neck.Consequently, the diameter of distal neck 128 typically is less than theinner diameter of proximal neck 124 because the catheter tubing isnarrower along the distal neck due to the termination of the ballooninflation lumen proximally of distal neck 128.

[0044] Dilatation balloon 108 is desirably made from PET (polyethyleneterephthalate). Other suitable materials include polyethylene, polyvinylchloride, Surlyne polyethylene ionomer copolymer, Pebax®polyamide-polyether-polyester block copolymer, PBT (polybutyleneterephthalate), poly (butylene terephthalate)-block-poly (tetramethyleneoxide), Arnitel, Hytrel, polyetherether ketone (PEEK), Teflon,polytetrafluoro-ethylene (PTFE), nylon (for example, nylon 12), andtheir copolymers as well as other polyolefins and silicone elastomers.Other suitable balloon materials are disclosed in PCT publication WO97/32624 and commonly assigned U.S. application Ser. No. 08/926,905.More generally, suitable materials include a polymeric material that issufficiently pliable or formable to readily achieve the enlargedconfiguration, yet is relatively inexpansible, tending to maintain theconfiguration shown in FIG. 1 under increased fluid pressure within theballoon. Of course, the material should be biocompatible.

[0045] As shown in FIG. 2, catheter tubing 104 has a central lumen 132to accommodate a guide wire (not shown) and, if desired, to provide apath for supplying drugs from the proximal end of the catheter tubing toa treatment site. A broken line at 134 indicates the proximal boundaryof a fusion bond 136 between catheter tubing 104 and distal neck 128.Fusion bond 136 is annular, and is located along the interface betweenthe distal neck and the catheter tubing. More particularly, thepolymeric material along the inside surface of distal neck 128 and thepolymeric material along the exterior surface of tubing 104 become fusedand form the bond as they cool and solidify, to provide a fluid tightseal between the catheter tubing and the balloon.

[0046] Desirably, bond 136 has an axial dimension of at most 0.030inches, and is within 0.030 inches of distal cone 120, for a length ofthe catheter distal tip (including distal neck 128 and the distal end ofcatheter tubing 104) of at most 0.060 inches. More desirably, the axialdimension of the bond is about 0.020 inches, and the bond is within0.010 inches of cone 120. Further, the distal cone is substantially freeof undesirable crystallization that results from thermal shock from theheat of bond formation.

[0047] In accordance with the present invention, fusion bonds betweenthe catheter tubing and balloon are formed by a non-contact process,resulting in bonds that are much narrower yet withstand burst pressureto the same degree as conventional bonds. Moreover, as compared toconventionally formed bonds, bonds formed according to the presentinvention can be positioned substantially closer to the cones of theballoon, without the crystallization or attendant stiffening.

[0048] An apparatus used in forming the inventive balloon catheter isillustrated schematically in FIG. 3. Catheter tube 104 is disposed aboutmandril 142 formed of stainless steel or other suitable material. Theoutside diameter of mandril 142 is approximately equal to the innerdiameter of catheter tube 104 so that the mandril receives cathetertubing 104 in sliding or slip fit fashion. Catheter tube 104 extendsthrough hole 168 in parabolic mirror 166 and is positioned such that thedesired bond region resides in the focal region of parabolic mirror 166.

[0049] Parabolic mirror 166 may also be split in half and provided inclam-shell like form, to facilitate positioning of the catheter.

[0050] A system for directing energy, desirably monochromatic energy,onto mandril 142, includes a laser source 146 which generates laser beam150. Desirably, beam 150 will have a wavelength in the infrared range.More desirably, the laser is a CO₂ laser operating at a wavelength ofabout 10.6 microns. The invention also contemplates the use of lasersoperating in the ultraviolet range. Other suitable lasers for useinclude diode lasers.

[0051] Beam 150, having a circular cross-section, is directed through afirst conical lens 154 which forms a diverging annular beam 156. Annularbeam 156 is directed through a second conical lens 158 which collimatesthe beam to produce a collimated annular beam 162. The collimated beamis then focused with parabolic mirror 166 into beam 167 which isdirected onto the entire circumference of catheter 104 at the desiredbond site. The focal size may be adjusted by varying the input diameterof the laser beam, the divergence angle of the first conical lens, theseparation between the first and second lenses and the focal length ofthe parabolic mirror.

[0052] The evolution of the beam is shown in FIG. 4 from a threedimensional perspective.

[0053] The focal size and focal intensity may be varied by varying theinput divergence angle of the laser or the focal length of the parabolicmirror.

[0054] Distal end 105 of the catheter 104 may further be supported by afixture held by wires which radiate from the optical axis through theannular beam and fixed in place externally as shown in FIGS. 5a-5 c.

[0055] As shown in FIGS. 5a and 5 b, a fixture, shown generally at 206,includes an annular portion 216 with a central support bar 218 extendingtherethrough. Central support bar 218 has an opening therein toaccommodate a mandril 142 therein. The opening may optionally extend thelength of the central support bar to accommodate a portion of a cathetertherein. Central support bar 218 may be made of any suitable materialincluding polymeric material or metal. Central support bar 218 issupported by three supports 217 extending from a first side of annularportion 216 and three supports 217 extending from a second side ofannular portion 216. The supports may be made of wire or other rigidmaterials including metal and polymeric materials. Additional or fewersupports may also be provided. Annular portion 216 is, in turn,supported by support 220. Support 220 may be of any suitable shape whichis capable of supporting fixture 206. Support 220 may optionally includeclamps or other devices for holding fixture 206 in place. An isometricview of fixture 206 is provided in FIG. 5b and an end view of fixture206 is provided in FIG. 5c.

[0056] Alternatively, the mandril may be supported by a suitablestructure such as a wire fixture extending from one of the lenses.

[0057] Another method of securing the distal end of the catheter isshown in FIG. 5d. Mandril 142 is held by fixture 210. Fixture 210 has anopening therein sized to receive mandril 142 therein. Fixture 210 may beattached to conical lens 158 through any suitable means including theuse of an adhesive.

[0058] Yet another suitable arrangement is shown in FIGS. 5e and 5 f. Afixture, shown generally at 206, includes a tip holder 210 for receivingmandril 142 therein. As shown in perspective in FIG. 5f, tip holder 210is attached to the center of window 214. Window 214 is transparent tothe laser radiation and placed between conical lens 158 and catheter104. Window 214 is mounted to or otherwise secured to annular ring 216.Desirably, window 214 will be made of ZnSe.

[0059] As shown in FIGS. 6 and 7, the inventive process may also bepracticed using an apparatus similar to that shown in FIG. 3 withoutsecond conical lens 158. In this case, diverging annular beam 156 isredirected and refocused using parabolic mirror 166 into beam 167 whichis directed onto the entire circumference of catheter 104 at the desiredbond site. The focal size may be adjusted by varying the input diameterof the laser beam and/or the focal length of the parabolic mirror. FIG.6 shows an embodiment with a small focus beam size. FIG. 7 shows anembodiment with a larger focus beam size.

[0060] The inventive process may also be carried out using thearrangement shown in —FIG. 8. Laser beam 150 is directed at conicalmirror 254. Reflected beam 156 is directed toward a second conicalmirror 258 where it is collimated. Collimated beam 162, reflected offsecond mirror 258 is annular and may be redirected by a parabolic mirror(not shown) toward a catheter or balloon in accordance with theinvention.

[0061] In accordance with the invention, a balloon catheter may beprepared by placing catheter tube 104 onto mandril 142. Optionally, arelatively short (0.25 inches) length of heat shrink tubing 172,desirably constructed of a polyolefin, may be disposed about cathetertube 104 as shown in FIG. 9 and suitably aligned. Balloon 108 isdisposed about catheter tube 104 in a desired location. Where heatshrink tubing is employed, the portion of the balloon to be bonded tothe catheter tube, typically the proximal and/or distal neck region, isinserted within heat shrink tubing 172. The balloon may also bepositioned about the catheter first and the heat shrink tubingsubsequently positioned over the desired portion of the balloon.

[0062] The region of the catheter and balloon assembly to be bonded isthen placed within the focal region of parabolic mirror 166 or, moregenerally, depending on the particular arrangement of optical equipment,within the focused annular beam 167. For example, where the intendedfusion bond width is 0.030 inches and the bond is to be spaced an axialdistance of 0.010 inches from the distal cone, the laser system is suchthat beam 167 is aligned on the intended center of the bond relative tothe distal cone, i.e. at 0.025 inches from the cone. The region to bebonded may also be held stationary and the laser and associated opticsadjusted to provide a focused annular beam at the bond region.

[0063] Once catheter tube 104, balloon 108 and optional heat shrinktubing 172 are properly positioned, a laser beam 150 of required energyis generated by laser source 146 and shaped and focused, as discussedabove, into annular beam 167 directed at the desired bond region, asshown in FIG. 3.

[0064] The concentration of energy necessary for fusion bonding at thebond site may be suitably controlled via several different parameters.First, the beam may be focused over a shorter or longer length ofpolymeric material. Where the beam is focused over a shorter length ofpolymeric material, the energy source may be operated at a lower wattageor for shorter duration. Second, where the energy source is a laser, thelaser beam will desirably have a profile which is constant orsubstantially constant across the beam diameter as shown in FIG. 10 or aprofile which is gaussian (TEM₀₀ mode) or substantially gaussian acrossthe beam diameter as shown in FIG. 11. Third, the wavelength of theenergy, desirably laser energy, and the polymeric materials of theballoon and catheter tubing will desirably be matched. That is, thepolymeric materials being bonded together will desirably have a highabsorptivity for energy at the selected wavelength (for example, 10.6microns in the case of a CO₂ laser).

[0065] Information on the absorptivity of various materials, withrespect to wavelength of the energy, is available, for example in TheInfrared Spectra Atlas of Monomers and Polymers, published by SadtlerResearch Laboratories. A more detailed discussion of the matching may befound in U.S. Pat. No. 5,501,759.

[0066] By suitably adjusting the focus of the beam and by providingenergy at one or more wavelengths that are selected to be stronglyabsorbed by at least one and desirably both of polymeric materials, heatsufficient to fuse an outer surface of the catheter tubing and an innersurface of distal neck of the balloon may be generated at a laser powerof less than 10 watts. A duration of about 0.5 seconds to about 3seconds of laser energy application has been found satisfactory forforming bonds that can withstand burst pressures exceeding 400 poundsper square inch, and the degree of control over the laser yields a highdegree of consistency among the bonds. Typically, the laser energy isapplied continuously for a period of 1 to 2 seconds at a power level of1 Watt. Desirably, the laser energy will be focused to an approximately1 mm wide annulus on the balloon. After the fused material cools andsolidifies, the heat shrink tubing if present is removed.

[0067] Because of the high absorptivity one or both of the polymericmaterials at the chosen wavelength(s), there is no substantialconduction of heat along the mandril in either axial direction away fromthe bond site. Also, the heat conductivity of polymers is low and thelaser is on for only a short period of time. Thus, there is no undueheating of portions of the tubing and balloon near the bond which wouldlead to crystallization and stiffening of the polymeric materials. Assuch, a distal bond can be positioned within 0.010 inches of the distalcone without any substantial crystallization or stiffening of the cone.

[0068] In another embodiment of the invention, a holographic opticalelement (HOE) or a diffractive element may be used in place of theconical lens to form the annular beam.

[0069] HOE's are well known in the art. An HOE is formed by overlappinga reference laser beam and a modified laser beam. An HOE of a lens, forexample, may be formed by mixing a reference laser beam with aconverging laser beam at a holographic plate. Subsequently, when a laserbeam identical to the reference beam is incident on the holographicplate, a converging beam emerges and the HOE behaves like a lens.

[0070] The HOE required for an emerging annular beam is formed by asimilar method. A reference laser beam and a diverging annular laserbeam (after passing through a conical lens) are directed so that theyare incident and overlapping on the holographic plate. The developedhologram has the property that when the reference laser beam is incidentthereon, the emerging laser beam is annular.

[0071] In yet another embodiment of the invention, an HOE, a diffractiveelement, a refractive element or reflecting element may be used to focusthe annular beam around the circumference of the catheter. Examples ofsuitable elements include a circular, elliptical or hyperbolic mirror orlens.

[0072]FIG. 12 illustrates the use of a refractive element in thepractice of another inventive embodiment of the invention. Energy source146, desirably a laser, generates beam 150 which is refocused via lens154 into annular beam 156. Lens 158 collimates annular beam 156.Refractive lens 268 then focuses collimated beam 162 onto catheter 104.

[0073] The invention further contemplates simultaneously bondingmultiple portions of a catheter. For example, both the proximal anddistal ends of a balloon may be bonded to a catheter simultaneously. AnHOE may be used to produce two or more annular beams which may then befocused to both the proximal end and the distal end of the balloon. AnHOE for two or more annular beams is produced by multiple exposure of aholographic plate using different conical lenses with different conicalangles. For example, for a two annular beam hologram the holographicplate is first exposed to an overlapping reference beam and a divergingbeam from a conical lens of a first cone angle A. The holographic plateis then exposed to the same reference beam and a diverging beam from adifferent conical lens of a second cone angle B. After processing, thehologram will produce two diverging annular beams when illuminated withthe reference beam.

[0074] The proximal and distal ends of the balloon may also benon-simultaneously bonded to a catheter using separate annular beamsgenerated by an HOE. Two different HOE's are used to achieve thiseffect. The laser is directed to each one in turn. The same effect mayalso be achieved using a single HOE with two different areas.

[0075] Simultaneously bonding multiple portions of a catheter may alsobe accomplished using suitable beam splitting techniques to split aninitial energy beam into two beams and then focusing each of the beamsinto an annular beam. Simultaneous bonding may also be accomplished byusing two or more laser sources as shown, for example, in FIG. 13. Asshown in FIG. 13, two laser sources 146 a,b are provided. First lasersource 146 a generates a first beam 150 a which is conditioned with twoconical lenses 154 a and 158 a to form annular beam 162 a. Similarly,second laser source 146 b generates a second beam 150 b which isconditioned with two conical lenses 154 b and 158 b to form annular beam162 b. Annular beams 162 a,b are reflected inward by parabolic mirror166. Parabolic mirror 166 is a bifocal parabolic mirror comprising asmaller focal length portion 166 a and a larger focal length portion 166b. Reflected beams 167 a,b impinge on catheter 168 at two locationsalong catheter 168. The arrangement of the optics is similar to that ofFIG. 3 with two lasers and optical systems rather than one.

[0076] The other single beam embodiments disclosed herein may similarlybe modified for use in simultaneously bonding.

[0077] The invention has been described above with respect to bonding apolymeric balloon material to a tubular body such as a catheter. Theinvention is also directed to a method of bonding a retention sleeve(such as for stents and grafts or other medical devices) or any othersuitable polymeric material to a catheter tube. As shown in FIG. 14,retention sleeve 176 is fusion bonded to catheter tube 104. Retentionsleeve 176 retains stent 180 on catheter tube 104. The bond is achievedusing the apparatuses disclosed herein by directing the energy at theretention sleeve in the desired bond region. The retention sleeve may bemade from elastic and compliant balloon materials, including materialsdisclosed in U.S. Pat. No. 6,068,634. Desirably, the retention sleevewill be made of a material which is radiopaque, at least in part.

[0078] As with the fusion bonding of a balloon, the retention sleevemust be suitably aligned about the desired portion of the catheter. Theretention sleeve must also be suitably aligned about the stent.Optionally, as with balloons, heat shrink tubing made be disposed aboutthe retention sleeve prior to fusion bonding. A beam of energy, asdiscussed above with respect to balloons, is then directed at the regionof the desired bond to bond the retention sleeve to the catheter tube.

[0079] The retention sleeve may be made of suitable polymeric materialsincluding the balloon materials disclosed above. Other suitablematerials as well as other details concerning retention sleeves may befound in U.S. application Ser. Nos. 09/407,836 and 09/427,805.

[0080] The inventive processes may also be used to bond together twocatheter tubes or a catheter tube and a sheath. An example of a catheterhaving a retractable sheath and a dual lumen tube is provided in U.S.Pat. No. 5,957,930. The retractable sheath disclosed therein may bebonded to the dual lumen tube using the inventive methods disclosedherein. The particular choice of energy wavelength will depend on theparticular materials used for the dual lumen tube. Other portions of thecatheter which may be bonded together using the inventive methodsinclude the slide sheath and the outer shaft, the bumpers and thecatheter shaft, the sliding seal and the outer shaft and the manifoldand a hypotube. More generally, those polymeric portions of a catheterwhich are currently bonded together using other techniques may beamenable to the inventive methods.

[0081] The invention is also directed more generally to a process forsealing a polymeric material to a polymeric catheter tube. The processcomprises the steps of selecting at least one wavelength of energy thatis at least partially absorbed by at least one of the polymeric materialand the polymeric catheter tube, generating at least one annular beam ofelectromagnetic energy at said selected energy wavelength, controllablydirecting the annular beam of energy onto the polymeric material toconcentrate the energy in a bond site circumscribing the catheter tubeto at least partially melt at least one material selected from the groupconsisting of the polymeric material and the polymeric catheter tubealong the bond site and the immediate region thereof and allowing atleast one partially melted polymeric material to cool and solidify toform a fusion bond between the tube and the polymeric material.

[0082] The invention is also directed to processes for bonding polymericmaterials to catheter tubes continuously about the periphery of thecatheter tube. The polymeric material may itself be in the form of atube or may be in the form of a sheet wrapped around the periphery ofthe catheter.

[0083] Other uses for the inventive processes include bonding polymericsheaths to catheter tubes, bonding sheet-like or tubular balloonprotectors to balloons or catheter tubes and bonding a catheter tip to acatheter. As with the bonding of balloons to catheters, an annular beamof energy is directed at the polymeric material and catheter in thedesired bonding region.

[0084] The invention is also directed to bonding polymeric materials tomedical balloons. For example, in the case of a catheter carrying aballoon expandable stent, a flexible sheath may be bonded to the medicalballoon about the periphery of the balloon in order to protect theballoon from any edges on the stent.

[0085] In another embodiment, the invention is directed to a process forforming a fluid tight seal between a polymeric body and a polymericmember surrounding the body. The process comprises the steps ofpositioning a polymeric member along and in surrounding relation to abody of polymeric material, with the polymeric member and body alignedto place a first surface portion of the polymeric member and a secondsurface portion of the body in a contiguous and confronting relation.The polymeric materials forming the body and the polymeric member havenon-uniform energy absorption spectra that include high absorptivitywavelength bands. At least one of the high absorptivity wavelength bandsof the polymeric material forming the body and at least one of the highabsorptivity wavelength bands of the polymeric member overlap oneanother in at least one range of overlapping wavelengths. Amonochromatic energy wavelength that is contained within at least one ofthe overlapping wavelength ranges is selected. An annular beam ofsubstantially monochromatic electromagnetic energy is generated at theselected monochromatic energy wavelength and controllably directed ontothe body and the polymeric member to concentrate the monochromaticenergy in a narrow bond site circumscribing the body and running alongthe interface of the first and second surface portions. The beam meltsthe polymeric materials along the bond site and the immediate regionthereof. Finally, the previously melted polymeric material is allowed tocool and solidify to form a fusion bond between the body and polymericmember.

[0086] Desirably, the polymeric member is a dilatation member and thepolymeric body is a catheter tube. Also desirably, the dilatation memberis a catheter balloon positioned along a distal end region of thecatheter tubing and includes proximal and distal neck portions, a medialregion having a diameter substantially larger than that of the neckportions, and proximal and distal tapered conical regions between themedial region and respective neck regions.

[0087] In another embodiment, the invention is directed to a process forsimultaneously bonding at least two polymeric materials to a cathetertube. The process comprises the steps of providing a catheter tubehaving at least a first predetermined bonding location and a secondpredetermined bonding location for bonding a polymeric material thereto,each bonding location having a polymeric material circumscribing thecatheter tube at the bonding location. A first annular beam ofelectromagnetic energy that is at least partially absorbed by thepolymeric material at the first bonding location and a second annularbeam of electromagnetic energy that is at least partially absorbed bythe polymeric material at the second bonding location are simultaneouslygenerated. The first and second annular beams of energy are controllablydirected onto the polymeric balloon material at the first and secondpredetermined bonding locations to concentrate the energy into the firstand second predetermined bond sites circumscribing the catheter tube andto at least partially melt the polymeric balloon material along the bondsites and the immediate regions thereof. The previously melted polymericmaterials in the first and second bonding locations are allowed tosolidify to form fusion bonds between the catheter tube and thepolymeric material at the first and second bonding locations.

[0088] In a further embodiment, the invention is directed to a processfor simultaneously welding the proximal and distal ends of a balloon toa catheter tube. In accordance with the inventive process, at least onewavelength of energy that is at least partially absorbed by the balloonis selected and a first annular beam of electromagnetic energy generatedat the selected energy wavelength and a second annular beam ofelectromagnetic energy generated at the selected energy wavelength. Thefirst annular beam is controllably directed toward the proximal end ofthe balloon to concentrate the energy in a narrow bond sitecircumscribing the catheter tube and running along the interface of thefirst and second surface portions, thus to melt the polymeric materialsalong the bond site and the immediate region thereof. The previouslymelted polymeric material is allowed to cool and solidify to form afusion bond between the catheter tube and the balloon. The secondannular beam is controllably directed toward the distal end of theballoon to concentrate the energy in a narrow bond site circumscribingthe catheter tube and running along the interface of the first andsecond surface portions, thus to melt the polymeric materials along thebond site and the immediate region thereof. The previously meltedpolymeric material at the distal end is allowed to cool and solidify toform a fusion bond between the catheter tube and the distal end of theballoon.

[0089] The frequency of the energy which is directed at the polymericmaterial in the inventive processes may be chosen such that the energyis at least partially absorbed by the balloon, by the polymeric cathetertube or by both the balloon and polymeric catheter tube. The energyshould be supplied at a sufficient power level as to cause at least oneof and preferably both of the balloon and polymeric catheter tube to atleast partially melt in the region of the desired bond.

[0090] Thus far, the energy has been described as monochromatic. Theinvention also contemplates the use of non-monochromatic energy as longas the energy is properly focused and of sufficient intensity to causemelting of the polymeric material to which it is directed. As such,multiple frequencies of energy may be employed as long as the energycontains one or more frequencies which are strongly absorbed by at leastone of the polymeric materials. Desirably, substantially all of thefrequencies of energy will be strongly absorbed by at least one of thepolymeric materials.

[0091] The inventive processes may also be used to bond togethermultiple layers of polymeric materials. For example, the inventiveprocesses may be used to simultaneously bond a stent retention sleeve toa balloon and the balloon to a catheter. This would, of course, requireproper alignment of the balloon, retention sleeve and catheter. Alsodesirably, the balloon, retention sleeve and catheter will all stronglyabsorb energy of same wavelength or will all have overlapping absorptionbands.

[0092] The invention may also be used to join together tubular membersthat have a non-circular cross-section. Thus, for example, the inventiveprocesses may be used to bond a balloon to a tube with an ellipticalcross-section. In order to achieve substantially uniform heating aboutthe elliptical periphery of the balloon or other tube, it is desirableto substitute the parabolic reflecting mirror with a mirror with across-section which is the same shape as the tube to be processed. Itwill be readily recognized that through the use of suitable lenses andreflecting mirrors, substantially uniform heating of tubes with othercross-sectional shapes may be achieved as well.

[0093] The invention is also directed to a process for selectivelywelding or bonding a material to a portion of the circumference orperiphery of a catheter or other tube. As shown in FIGS. 15a and 15 b,an annular laser beam 162 is generated and a portion of the beam blockedvia beam block 169. Portion 162 a of beam 162 reflects off of parabolicmirror 166 and onto catheter 104. Portion 162 b of beam 162 is blocked.Annular beam 162 may be generated using any of the apparatuses disclosedabove. Where the beam is generated using a conical lens (not shown),beam block 162 may be placed in between the conical lens and theparabolic reflector 166. The beam block may also be placed elsewhere.For example, a beam block may be placed between the parabolic reflectorand the catheter. The beam block may be any suitable material to block aportion of the annular laser beam. A beam block may also be implementedby altering and/or destroying the reflective properties of a desiredportion of the parabolic reflector. Similarly, an annular beam with aportion or segment blocked or absent may be created by a modifiedconical lens or HOE. By blocking a portion of the beam or providing abeam with a segment absent, a weld or bond which extends only part ofthe way around the catheter may be achieved.

[0094] Selectively welding only a portion of the circumference orperiphery of the catheter may prove beneficial in catheter formation,such as in the region of the port bond where a guidewire enters acatheter in mid-section on monorail catheters.

[0095] The invention may also be practiced by moving the catheteraxially during the application of laser energy. This allows foradditional control of the amount of energy delivered to the bondingsite. When movement of the catheter is slow, more power is delivered tothe bonding site. When movement of the catheter is fast, less power isdelivered to the bonding site. Moreover, in this way, a longer weld orbond may be achieved. This may prove particularly useful in welding asoft tip onto the end of a catheter tube where, typically, weld lengthsare from about 2 mm to about 55 mm in length. When the catheter is movedalong the optical axis during welding, the focussed annular beameffectively moves along the catheter thereby creating a continuous bondor weld of desired length. The same effect may also be achieved bymoving the parabolic mirror or the focussing lens.

[0096] Varying the movement speed of the catheter or parabolic mirrormay also be beneficial where the thickness of the materials to be weldedvaries along the length of the region to be welded. Where a thickerregion is encountered, the rate of movement of the catheter may beslowed down to apply more energy thereto. Where a thinner region isencountered, the rate may be increased as less energy is needed to heatthe material.

[0097] Finally, the invention is directed to the novel apparatusesdisclosed herein, including those apparatuses made using the inventiveprocesses disclosed herein.

[0098] In addition to the specific embodiments claimed below, theinvention is also directed to other embodiments having any otherpossible combination of the dependent features claimed below.

[0099] The above Examples and disclosure are intended to be illustrativeand not exhaustive. These examples and description will suggest manyvariations and alternatives to one of ordinary skill in this art. Allthese alternatives and variations are intended to be included within thescope of the attached claims. Those familiar with the art may recognizeother equivalents to the specific embodiments described herein whichequivalents are also intended to be encompassed by the claims attachedhereto.

1. A process for bonding at least one polymeric material to a polymericcatheter tube having a longitudinal axis, comprising the steps of:over-lapping a portion of the at least one polymeric material with aportion of the polymeric catheter tube thereby creating an over-lappedportion; generating an annular beam of electromagnetic energy such thata region enclosed by said annular beam is substantially absent ofelectromagnetic energy, said annular beam being directed so that thelongitudinal axis of the catheter tube traverses said region of theannular beam; and redirecting at least a portion of the annular beamsuch that it converges on the polymer material at the overlapped portioncircumscribing at least a portion of the polymeric catheter tube to atleast partially melt at least one material selected from the groupconsisting of the polymeric material and the polymeric catheter tubealong at least a portion of the overlapped portion.
 2. The process ofclaim 1 wherein the polymeric material is a polymeric balloon material.3. The process of claim 1 wherein the electromagnetic energy issubstantially monochromatic.
 4. The process of claim 1 wherein theelectromagnetic energy is not substantially monochromatic.
 5. Theprocess of claim 2 wherein the energy is at least partially absorbed bythe polymeric balloon material and the polymeric catheter tube.
 6. Theprocess of claim 1 wherein the polymeric material is formed from apolymer selected from the group consisting of: polyesters, polyolefins,polyamides, thermoplastic polyurethanes and their copolymers,polyethylene terephthalate, nylon, and combinations thereof.
 7. Theprocess of claim 2 wherein the energy is at least partially absorbed bythe polymeric balloon material causing the polymeric balloon material toat least partially melt.
 8. The process of claim 2 wherein the energy isat least partially absorbed by the polymeric catheter tube causing thepolymeric catheter tube to at least partially melt.
 9. The process ofclaim 1 wherein the polymeric material is a retention sleeve.
 10. Theprocess of claim 1 wherein the annular beam has a substantially circularcross-section.
 11. The process of claim 1 wherein the annular beam has anon-circular cross-section.
 12. The process of claim 1 wherein thegenerating step further comprises the steps of: generating a collimatedoptical beam; directing the collimated optical beam through a firstoptical element to generate a diverging optical beam; and directing thediverging optical beam through a second optical element to thereby formthe annular beam.
 13. The process of claim 12 wherein at least one ofsaid first and second optical elements is a conical lens.
 14. Theprocess of claim 12 wherein at least one of said first and secondoptical elements is selected from the group consisting of a holographicoptical element or a diffractive element.
 15. The process of claim 12wherein said first and second optical elements each comprise a conicallens.
 16. The process of claim 1 wherein the redirecting step includesthe step of reflecting at least a portion of the annular beam.
 17. Theprocess of claim 16 wherein the reflecting step is performed by aparabolic mirror.
 18. The process of claim 17 further comprising thestep of locating the over-lapped portion in the focal region of themirror.
 19. The process of claim 1 further comprising the step ofapplying a heat shrink tubing about said overlapped portion.
 20. Theprocess of claim 1 wherein the generating step further comprises thesteps of: generating an optical beam; directing the optical beam to aconical mirror to generate first and second reflected optical beamstraveling in substantially opposite directions from one another;re-directing the first and second reflected optical beams to first andsecond collimating mirrors, respectively, such that said redirectedfirst and second beams are parallel to one another to therebycollectively form the annular beam.
 21. The process of claim 1 whereinthe redirecting step includes the step of redirecting at least a portionof the annular beam such that it converges on the polymer material atthe overlapped portion circumscribing substantially all of the polymericcatheter tube.
 22. The process of claim 1 further comprising the step ofblocking a portion of the annular beam to prevent the annular beam fromconverging on the polymer material at all of the overlapped portioncircumscribing the polymeric catheter tube.
 23. A process for bonding atleast one polymeric material to a polymeric catheter tube having alongitudinal axis, comprising the steps of: over-lapping a first portionof the at least one polymeric material with a first portion of thepolymeric catheter tube thereby creating a first over-lapped portion;generating a first annular beam of electromagnetic energy such that aregion enclosed by said annular beam is substantially absent ofelectromagnetic energy, said first annular beam being directed so thatthe longitudinal axis of the catheter tube traverses said region of theannular beam; and redirecting at least a portion of the first annularbeam such that it converges on the polymer material at the firstoverlapped portion circumscribing at least a portion of the polymericcatheter tube to at least partially melt at least one material selectedfrom the group consisting of the polymeric material and the polymericcatheter tube along at least a portion of the first overlapped portion;over-lapping a second portion of the at least one polymeric materialwith a second portion of the polymeric catheter tube thereby creating asecond over-lapped portion; generating a second annular beam ofelectromagnetic energy such that a region enclosed by said secondannular beam is substantially absent of electromagnetic energy, saidsecond annular beam being directed so that the longitudinal axis of thecatheter tube traverses said region of the second annular beam; andredirecting at least a portion of the second annular beam such that itconverges on the polymer material at the second overlapped portioncircumscribing at least a portion of the polymeric catheter tube to atleast partially melt at least one material selected from the groupconsisting of the polymeric material and the polymeric catheter tubealong at least a portion of the second overlapped portion.
 24. Theprocess of claim 23 wherein the first and the second overlapped portionsare proximal and distal ends of the polymeric material, respectively.25. The process of claim 23 wherein the steps of redirecting at least aportion of the first annular beam and the second annular beam areperformed simultaneously.
 26. The process of claim 23 wherein the stepsof redirecting at least a portion of the first annular beam and thesecond annular beam are performed sequentially.
 27. The process of claim23 wherein the polymeric material is a polymeric balloon material. 28.The process of claim 23 wherein the electromagnetic energy issubstantially monochromatic.
 29. The process of claim 23 wherein theelectromagnetic energy is not substantially monochromatic.
 30. Theprocess of claim 27 wherein the energy is at least partially absorbed bythe polymeric balloon material and the polymeric catheter tube.
 31. Theprocess of claim 23 wherein the polymeric material is formed from apolymer selected from the group consisting of: polyesters, polyolefins,polyamides, thermoplastic polyurethanes and their copolymers,polyethylene terephthalate, nylon, and combinations thereof.
 32. Theprocess of claim 27 wherein the energy is at least partially absorbed bythe polymeric balloon material causing the polymeric balloon material toat least partially melt.
 33. The process of claim 27 wherein the energyis at least partially absorbed by the polymeric catheter tube causingthe polymeric catheter tube to at least partially melt.
 34. The processof claim 23 wherein the polymeric material is a retention sleeve. 35.The process of claim 23 wherein the first and second annular beams eachhave a substantially circular cross-section.
 36. The process of claim 23wherein the first and second annular beams each have a non-circularcross-section.
 37. The process of claim 23 wherein the step ofgenerating a first annular beam further comprises the steps of:generating a first collimated optical beam; directing the firstcollimated optical beam through a first optical element to generate afirst diverging optical beam; and directing the first diverging opticalbeam through a second optical element to thereby form the first annularbeam.
 38. The process of claim 37 wherein at least one of said first andsecond optical elements is a conical lens.
 39. The process of claim 37wherein at least one of said first and second optical elements isselected from the group consisting of a holographic optical element or adiffractive element.
 40. The process of claim 37 wherein said first andsecond optical elements each comprise a conical lens.
 41. The process ofclaim 23 wherein the redirecting steps include the steps of reflectingat least a portion of the first and second annular beam.
 42. The processof claim 41 wherein the reflecting step is performed by a parabolicmirror.
 43. The process of claim 42 wherein the parabolic mirror is abifocal parabolic mirror having two surface portions with differentfocal lengths.
 44. The process of claim 42 further comprising the stepof locating the first over-lapped portion in the focal region of themirror.
 45. The process of claim 1 further comprising the step ofapplying a heat shrink tubing about said first and second overlappedportions.
 46. The process of claim 23 wherein the redirecting stepincludes the step of redirecting at least a portion of the first annularbeam such that it converges on the polymer material at the firstoverlapped portion circumscribing substantially all of the polymericcatheter tube.
 47. The process of claim 23 further comprising the stepof blocking a portion of the first annular beam to prevent the annularbeam from converging on the polymer material at all of the firstoverlapped portion circumscribing the polymeric catheter tube.